Cooling device for telephone-transmitters.



{ 0. E. Benin 9 J. HOLMSTRUM. COOLING DEVICE FOR TELEPHONE TRANSMITTBRS,

APPLIGAIION FILED 116?. 2 1910.

' Patented July 25, 1911.

UNITED STATS CARL EMIL EGNER, 0F STOCKHOLM, AND JOHAN GUNNAR HOLMSTRiIllYl, OF SALTSJG- s'roRANGEN, SWEDEN.

COOLING DEVICE JiOB TELEPHONE-TRANSMITTERS.

To (171 whom it may concern:

B it known that we, om. EMIL Eoxn n, a subject'of the King of Sweden, and resident of Blekingegatan 53, Stockholm, in the Kingdom of Sweden, and JOIIAN GUXNAR llOLMS'tRtiM, a subject of the King of Sweden, and resident of Saltsjti-Storiingen, in the Kingdom of Sweden, have invented certain new and useful lmprovements in Cooling Devices; for Telephone-Transmitters, of, which the'following is a specification, 'refe'rence being had therein to the accompanying drawing. f L in our pending application for U. S. Letters latent Ser. No. 551688 a cooling device for telephonetransmitters is described, in which the electrodes are cooled by a certain quantity of liquid or a solid body of a low melting point incloscd in a receptacle in the "transmitter;

.This invention relates to an improvement of the said cooling device.

Figure '1 in the accompanying drawing is a cross section of a transmitter provided with the improved cooling device. Fig. 2 is a front view of the transmitter; the diaphragm and mouthpiece being omitted.

'l is the diaphragm and 2 the electrode oscillating within the same. The stationary electrodes 3, l, 5 and (3, four in number, are tixed to the inner wall 7 of the transmitter asing. The electrodes 3 and 5 are in metallic contact with the wall 7, while the electrodes l and 6 are insulated from the said wall by means of an intermediate. layer of ebonite or the like. The wall 7 forms the side wall of a receptacle 8, which provided in the transmitter casing and is tilled or partially tilled with a cooling liquid 9. In he rear wall of the transmitter easing an opening it) is provided. through which the said liquid is poured into the box, the said open ing being then hermetically sealed by a cover 11. The carbon-grains are denoted by 1% and the means for int-losing the g d115, felt orthe like, by 15.

flhe electrodes 3, 4, 5 and t3 ought to be made of a metal of a great heat coiuluctivity, for instance silver, copper, and are preterably cored out from their inner ends, so that cooling liquid is loc ted as near as possible .to the surfaces of lie electrodes.

As stated above, two of the stationary electrodes viz. 2 and 5 are in metallic contact with the cooling box 2'. c. with the transmit- Specification of Letters Patent.

Application filed November 2, 1910.

Patented July 25, 1911.

Serial No. 590,334.

in some cases. The insulated electrodes are each provided with a cohnecting screw 12 and 13 respectively for the conducting wires.

The transmitter may, as easily understood by those skilled in the art, be used either as a single acting or as a double actingtransmitter. ltn the 't'ormci case all the stationary electrodes 3,4, 5 and 6 are connected by metallic,conductors and the current passes through the carbon-grain cells to the oscillating electrode 2 and then to the diaphragm 1. Consequently, the four cells are connected in parallel. In the latter use the two insulated electrodes 4 and 6 are connected by a suitable wire. The current passes from the said electrodes 4: and 6 in parallel through their carbon cells to the electrode 2 and then back through the carbon cells of the two other electrodes 3 and 5 and from these electrodes 2% and 5 to the casing of the transmitter. Consequently, the carbon-grain cells are connected two in parallel and two in series. All the cells may, if wanted, be connected in series. For thatpurposethe oscillating electrode 2 is divided into two halves, one insulated from the other. In such case the current passes to the electrode 4, for instance, then through the first carbon-grain cell to the one part of the electrode from the said part through the second cell to the electrode 3, through the casing of the transmitter to the electrode the: third cell, the other part of the electrode 2, the fourth cell and the electrode 6. Consequcntly by providing the transmitter with a number of suitable connecting screws the four cells of the transmitter can be connected by an easily efi'ected shifting of the wires, either in series, two by tiwo, or in parallel, according as a greater or less resistance in the transmitter is wanted. The cells must not necessarily be four in number, as dcscribed above and shown in the drawing,

lot;

till

have substantially the same temperature.

Consequently, the heat generated in the electrodes is distributed in the whole cooling box, so that a too great increasing of the temperature in the carbon-grain cells is ob-' viated.

The described cooling box LI-ll'SOlQSOd, so thatabsorbing of heat, effected oy thqevapcrating of the liquid, is dispensed with. A small air. chamber must evidently be provided in the box, in order that the liquid may not break the box, when expanded by the absorbed heat. A safety valve may be provided, if necessary, which will open, if the pressure increases to a too great extent. A safety valve is necessary, if such a cooling liquid is used, for instance distilled Water, inwhich a generating of gas caused by electrolysis is to be feared. The box may, evidently, be open, so that evaporation can take I place, and this arrangement is suitable, if specially strong currents are used in the transmitter.

Having now described our invention, what we claim as new and desire to secure by Letters Patent is 1. In a telephone transmitter, the combination of a receptacle containing a cooling liquid exerting great resistance to the elecaaaom tric current and electrodes in direct contact with the said liquid, substantially as described and for the purpose set forth.

2. In a telephone transmitter, the combination of a receptacle containing a cooling liquid exerting great resistance to the electric current and electrodes cored outfrom their inner ends, the said electrodes communicating with the said receptacle and also containing a cooling liquid, substantially as described and for the purpose set forth.

3. In a telephone transmitter the combination of a chamber containing a cooling liquid, exerting great resistance to the electric current, and a number of electrodes insulated fr0m the said chamber and in direct contact with the said liquid, substantially as described and for the purpose set forth.

4. In a telephone transmitter the combination of a chamber containing a cooling liquid, exerting great resistance to the electric current, and a number of electrodes, insulated from the said chamber and cored out from their inner ends, the said electrodes communicating with the said chamber and also containing cooling liquid, substantially as described and for the purpose set forth.

In witness whereof, We have hereunto signedour names in the presence of two subscribing Witnesses.

CARL EMIL nouns. J OHAN GUNNAR HOLMS'TROM. Witnesses HEDING MELINDER, ROBERT ArnLsnEN. 

